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The Periodic Table
and Periodic Law
Periodic trends in the properties of atoms allow us to predict
physical and chemical properties.
Section 1: Development of the Modern Periodic
Table
Section 2: Classification of the Elements
Section 3: Periodic Trends
Essential Questions
• Section 1: The periodic table evolved over time as
scientists discovered more useful ways to compare and
organize the elements.
• Section 2: Elements are organized into different blocks in
the periodic table according to their electron
configurations.
• Section 3: Trends among elements in the periodic table
include their sizes and their abilities to lose or attract
electrons.
• How was the periodic table developed?
• What are the key features of the periodic table?
• Why do elements in the same group have similar properties?
• Based on their electron configurations, what are the four
blocks of the periodic table?
• What are the period and group trends of different properties?
• How are period and group trends in atomic radii related to
electron configuration?
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Section 1: Development of the Modern Periodic Table
Vocabulary
Review
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atomic number
valence electron
principal energy level
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periodic law
group
period
representative element
transition element
metal
alkali metal
alkaline earth metal
transition metal
inner transition metal
lanthanide series
actinide series
nonmetal
halogen
noble gas
metalloid
ion
ionization energy
octet rule
electronegativity
The periodic table evolved over time as scientists discovered
more useful ways to compare and organize the elements.
Essential Questions
Vocabulary
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How was the periodic table developed?
Review
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What are the key features of the periodic table?
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atomic number
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Copyright © McGraw-Hill Education
periodic law
group
period
representative element
transition element
metal
alkali metal
alkaline earth metal
transition metal
inner transition metal
lanthanide series
actinide series
nonmetal
halogen
noble gas
metalloid
Development of the Modern Periodic Table
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Development of the Periodic Table
In the 1700s, Lavoisier compiled a list of all the known elements of the
time.
Development of the Periodic Table
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The 1800s brought large amounts of information and
scientists needed a way to organize knowledge about
elements.
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John Newlands proposed an arrangement where elements
were ordered by increasing atomic mass.
Development of the Periodic Table
Development of the Periodic Table
Newlands noticed when the
elements were arranged by
increasing atomic mass, their
properties repeated every
eighth element.
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Meyer and Mendeleev both demonstrated a connection
between atomic mass and elemental properties.
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Moseley rearranged the table by increasing atomic number,
and resulted in a clear periodic pattern.
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Periodic repetition of chemical and physical properties of the
elements when they are arranged by increasing atomic
number is called periodic law.
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The Modern Periodic Table
The modern periodic table contains boxes that contain the
element's name, symbol, atomic number, and atomic mass.
The Modern Periodic Table
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Columns of elements are called groups.
The Modern Periodic Table
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Elements are classified as metals, nonmetals, and metalloids.
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Metals are elements that are generally shiny when smooth and clean,
solid at room temperature, and good conductors of heat and
electricity.
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Rows of elements are called periods.
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Elements in groups 1,2, and 13–18 possess a wide variety of
chemical and physical properties and are called the
representative elements.
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Alkali metals are all the elements in group 1 except hydrogen, and
are very reactive.
Elements in groups 3–12 are known as the transition metals.
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Alkaline earth metals are in group 2, and are also highly reactive.
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The Modern Periodic Table
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The transition elements are divided into transition metals and
inner transition metals.
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The two sets of inner transition metals are called the
lanthanide series and actinide series and are located at the
bottom of the periodic table.
The Modern Periodic Table
The Modern Periodic Table
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Nonmetals are elements that are generally gases or brittle,
dull-looking solids, and poor conductors of heat and
electricity.
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Group 17 is composed of highly reactive elements called
halogens.
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Group 18 gases are extremely unreactive and commonly
called noble gases.
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Metalloids, such as silicon and germanium, have physical
and chemical properties of both metals and nonmetals.
Review
Essential Questions
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How was the periodic table developed?
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What are the key features of the periodic table?
Vocabulary
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periodic law
group
period
representative
element
• transition element
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metal
alkali metal
alkaline earth metal
transition metal
inner transition
metal
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lanthanide series
actinide series
nonmetal
halogen
noble gas
metalloid
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Section 2: Classification of the Elements
Essential Questions
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Why do elements in the same group have similar properties?
Elements are organized into different blocks in the periodic table
according to their electron configurations.
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Based on their electron configurations, what are the four blocks of the
periodic table?
Vocabulary
Organizing the Elements by Electron Configuration
Review
Recall electrons in the highest principal energy level are called valence
electrons. All group 1 elements have one valence electron.
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valence electron
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Organizing the Elements by Electron Configuration
Group 2 elements have
two valence electrons.
The number of valence
electrons for elements in
groups 13–18 is ten less
than their group number.
The energy level of an
element’s valence
electrons indicates the
period on the periodic
table in which it is found.
The s-, p-, d-, and f-Block Elements
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s-block elements consist of group 1 and 2, and the element
helium.
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Group 1 elements have a partially filled s orbital with one
electron.
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Group 2 elements have a completely filled s orbital with two
electrons.
The s-, p-, d-, and f-Block Elements
The shape of the periodic table becomes clear if it is divided into blocks
representing the atom’s energy sublevel being filled with valence
electrons.
The s-, p-, d-, and f-Block Elements
Groups 13–18 fill the p orbitals. In group 18, both the s and p
orbitals of the period’s principal energy level are completely filled.
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The s-, p-, d-, and f-Block Elements
The s-, p-, d-, and f-Block Elements
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The f-block contains the inner transition metals.
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f-block elements have filled or partially filled outermost s
orbitals and filled or partially filled 4f and 5f orbitals.
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The 7f orbitals hold 14 electrons, and the inner transition
metals span 14 groups.
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The d-block contains the transition metals and is the largest
block.
There are exceptions, but d-block elements usually have
filled outermost s orbitals, and filled or partially filled d
orbitals.
The five d orbitals can hold 10 electrons, so the d-block
spans ten groups on the periodic table.
Review
Section 3: Periodic Trends
Essential Questions
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Why do elements in the same group have similar properties?
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Based on their electron configurations, what are the four blocks of
the periodic table?
Trends among elements in the periodic table include their sizes
and their abilities to lose or attract electrons.
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Essential Questions
Vocabulary
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What are the period and group trends of different properties?
Review
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How are period and group trends in atomic radii related to
electron configuration?
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principal energy level
Atomic Radius
Atomic Radius
Atomic size is a periodic trend
influenced by electron configuration.
For metals, atomic radius is half the
distance between adjacent nuclei in a
crystal of the element.
For elements that occur as
molecules, the atomic radius is
half the distance between nuclei
of identical atoms that are
chemically bonded together.
ion
ionization energy
octet rule
electronegativity
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Atomic Radius
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Atomic radius generally decreases from left to right, caused by
increasing positive charge in the nucleus. Valence electrons are
not shielded from the increasing nuclear charge because no
additional electrons come between the nucleus and the valence
electrons.
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Atomic radius generally increases as you move down a group.
The outermost orbital size increases down a group, making the
atom larger.
Ionic Radius
When atoms lose electrons and form positively charged ions,
they always become smaller for two reasons:
Atomic Radius
Ionic Radius
When atoms gain electrons, they can become larger, because
the addition of an electron increases electrostatic repulsion.
1. The loss of a valence electron can leave an empty outer
orbital, resulting in a smaller radius.
2. Electrostatic repulsion decreases allowing the electrons to
be pulled closer to the nucleus.
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Ionic Radius
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The ionic radii of positive ions generally decrease from left to
right.
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The ionic radii of negative ions generally decrease from left
to right, beginning with group 15 or 16.
Ionic Radius
• Both positive and
negative ions increase
in size moving down a
group.
Ionization Energy
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Ionization energy is defined as the energy required to
remove an electron from a gaseous atom.
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The energy required to remove the first electron is called the
first ionization energy.
Ionization Energy
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Ionization Energy
Ionization Energy
Removing the second electron requires more energy, and is
called the second ionization energy.
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First ionization energy
increases from left to
right across a period.
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First ionization energy
decreases down a
group because atomic
size increases and
less energy is required
to remove an electron
farther from the
nucleus.
Ionization Energy
Electronegativity
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The ionization at which the large increase in energy occurs is
related to the number of valence electrons.
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The electronegativity of an element indicates its relative
ability to attract electrons in a chemical bond.
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The octet rule states that atoms tend to gain, lose or share
electrons in order to acquire a full set of eight valence
electrons.
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Electronegativity decreases down a group and increases left
to right across a period.
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The octet rule is useful for predicting what types of ions an
element is likely to form.
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Electronegativity
Review
Essential Questions
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What are the period and group trends of different properties?
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How are period and group trends in atomic radii related to electron
configuration?
Vocabulary
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ion
ionization energy
octet rule
electronegativity
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